As technologies for bonding a material A and a material B, there exist:
(1) A bonding technology using mechanical means (for example, bolts and nuts, or rivets),
(2) A bonding technology using welding means (for example, solders or brazing filler metals), and
(3) A bonding technology using adhesives
The aforementioned bonding technology (3) is employed in a wide-range fields. However, with regard to the adhesives to be employed for boding (adhesion) between the material A and the material B, it cannot be safely said that any type of the adhesives may be used. It is of importance to select the adhesives suitable for the material A and the material B. The adhesion conditions are also of importance. This means that employment of the conventional bonding technology (3) is not a simple matter. That is, the bonding technology employing the adhesives used so far is unsatisfactory.
A basis (basic point) of the adhesion by the conventional adhesives is founded on a phenomenon “wetting”. The aforementioned “wetting” phenomenon is governed by a kind of materials, a surface status (properties) of materials, an environment in the neighborhood, and the like. This has commonality with the fact that selection of the adhesives and selection of the adhesion conditions are of importance.
“Wetting” obeys to a law of free energy to be derived from a law of thermodynamics. Wetting of fluid for non-fluid is expressed by an interaction constant χ of both. χ existing in a scope of the wetting is 0 to 0.5. χ is comprised of an entropy term and an enthalpy term. In a high polymerized material (polymer), the aforementioned entropy term is approximately 0.34 in an experimental manner. The aforementioned χ is 0 to 0.45 when the wetting property is excellent. Thus, the remaining enthalpy term is at most 0.11 when the wetting property is excellent. The utilizable adhesion wetting is only 22% in terms of contribution when the interaction constant χ between the fluid and the non-fluid is 0.5. In such a manner, upon mentioning the wetting, a ratio of the wetting contributing to the adhesion is 22% of the entire wetting or less. This means that it is possible to manipulate adhesion factors only in very narrow scope. That is, the adhesion by the conventional adhesives is adhesion that is high in material dependency. And, the adhesion technology having a philosophy that an original point of the adhesion is “wetting” is high in material dependency. And yet, the intentional adhesion is difficult. In addition, reliability of the adhesion as well becomes a subject of discussion because an adhesive strength depends on the wetting (namely, intermolecular force). For example, the aforementioned wetting (namely, intermolecular force: adhesive strength) also fluctuates when the environment in which an adhesive interface exists is changed due to the adhesives. This causes a reliability of the adhesion to decline.
The adhesives (which is sometimes referred to as “molecular adhesives” in this specification) applying the chemical bonding (chemical reaction) has been proposed by this inventor instead of the adhesives applying the conventional wetting (intermolecular force: physical force) (Patent literatures 1, 2, and 3, and non-patent literatures 1, 2, 3, 4, and 5).